Personal computers “PCs” are now ubiquitous, at least in developed countries. PCs come in various form factors, including desktop models, towers, laptops, handheld devices, tablet PCs, etc. As such, the term PC or personal computer is used herein in a very broad sense, and is intended to include a wide variety of computing devices, including but not limited to the kinds just mentioned. By contrast, the term PC, as used herein, would probably not include so-called mainframe computers or other systems or clusters intended to service large numbers, e.g., thousands, of simultaneous users or tasks.
PCs, of which there are now millions in use, can be found in homes and businesses large and small. Since the advent of the PC, somewhere around 1980, they have become dramatically smaller, faster, and cheaper. For most applications, software now provides graphical user interfaces (GUIs) that enable even unsophisticated users to accomplish substantial computing tasks. That being said, using, maintaining and upgrading a modern PC is challenging for most users. In the corporate environment, many companies are large enough to afford an “IT” (information technology) department that can assist users with such tasks. In many smaller businesses and in homes (e.g., SOHO—small office/home office) situations, professional assistance is not readily available. In some cases, the user may employ on-line help or tutorials, but these resources are clumsy and few have the patience required to navigate them. In other cases, the user may pay hourly or per call charges for technical assistance.
To illustrate the burdens and challenges imposed on computer users, consider the following examples:                Replacing a failed disk drive        Restoring lost data resulting, e.g., from a failed memory device        Installing frequent updates to the operating system        Installing frequent software updates or patches to fix security issues        Adding more user memory (typically DRAM) or other hardware        Installing or upgrading driver software, such as printer drivers        Configuring the computer to use various network resources        Installing new application programsThere are other examples; these are merely illustrative. Some of these tasks are merely tiresome and annoying, while others require technical competence beyond that of most users. Until now, no current system has been developed to alleviate such burdens on computer users.        
Because most of the above-described problems stem from each user having to configure and maintain a separate PC, one approach has been to move as much of the processing as possible to central servers and allow users to access applications hosted by these central servers via the Internet. The burdens placed on the individual PCs are much less, since they only need to have basic Web browser functionality.
For example, Application Service Providers (ASPs) provide applications to individuals or organizations across the Internet or other network connections. Hosted applications can vary, but examples include financial applications (like general ledger or purchasing software) and office applications, e.g., word processors, spreadsheet programs, etc.
Unfortunately, the applications hosted by ASPs are often slow and not very responsive due to system load, network bandwidth, and latency issues. As a result, ASPs cannot generally guarantee a particular quality of service (QoS) for a given application.
Thin-client systems, like Citrix™, as well as emulation programs, such as Attachmate™, sometimes provide better performance. Attachmate™, for example, Web-enables legacy host applications. Such applications run on thin terminals, often in character mode (black screen dumb terminal). However, not every application can be made to work with emulation programs like Attachmate™. Furthermore, setting up these applications is complicated, typically requiring an IT professional to configure and maintain the application.
Another conventional technique that attempts to address the problems described above is virtual machine (VM) technology. VM technology allows multiple operating systems to run concurrently on a single machine. Each VM emulates the hardware and software of a stand-alone computer, including its CPU, sound, video, and network adapters, etc., in a self-contained, isolated environment.
In particular, Virtual PC™ and Virtual Server™, developed by Connectix and Microsoft, allow one or more legacy operating systems to run on the same computer system as the current Windows operating system. Today, many older x86-based operating systems are supported by Virtual PC and Virtual Server. Virtual PC for Mac allows for one or more other operating systems to run the Macintosh operating system, allowing users to run a Windows operating system and Windows applications on a Mac.
VM technology serves a variety of purposes. It enables hardware consolidation, because multiple operating systems can run on one computer. Key applications for VM technology include cross-platform integration as well as the following:                Legacy application migration. Legacy operating systems and applications can run on new hardware along with more recent operating systems and applications.        Server consolidation. If several servers run applications that consume only a fraction of the available resources, VM technology can be used to enable them to run side by side on a single server, even if they require different versions of the operating system or middleware.        Isolation for development, testing and technical support. Each VM acts as a separate environment, which reduces risk and enables developers to quickly recreate different operating system configurations or compare versions of applications designed for different operating systems. In addition, a developer can test an early version of an application in a VM without fear of destabilizing the system for other users.        Software demonstrations. VM technology allows users to recreate a clean operating system environment or system configuration quickly.        Courseware delivery and training. Organizations can configure and deploy a variety of training scenarios quickly.        Software distribution. IT groups can deliver prevalidated configurations for complex software solutions for fast deployment.        
Unfortunately, VM technology also has limitations. For example, an IT professional is generally required to create and set up each VM running on a Virtual Server. There is no automated method by which a novice user may remotely log into a Virtual Server and have a VM automatically created and initialized with all of the software and settings needed for the user to immediately begin working on a desired task.